Taxoids are compounds derived from taxol (also referred to as paclitaxel), an isolated natural product and an important anticancer drug. It stabilizes microtubules during mitosis to treat patients with different kinds of cancer (e.g. ovarian cancer, breast cancer and lung cancer). Natural taxol has been isolated from the stem bark of Yew. However, the extraction and purification of taxol from Yew are expensive.
Instead of obtaining taxol from Yew, semi-synthesis of taxol from a baccatin derivative (e.g. suitable protected 10-deacetylbaccatin III (10-DAB)) is a more economic way.

Preliminary studies by Potier's group (P.C.R. Acad. Sci. Paris II, 299, 1039, 1984; Tetrahedron 42, 4451, 1986) showed that the hydroxyl groups of 10-DAB have different reactivities toward acetic anhydride in pyridine. The relative reactivity was C(7)-OH>C(10)-OH>C(13)-OH>C(1)-OH. In 1988, Greene's group (J. Am. Chem. Soc., 110, 5917, 1988) reported the selective silylation of the C(7) hydroxyl group with triethylsilyl chloride in pyridine to produce 7-TES-10-DAB in 85% yield. The protected 10-DAB derivatives prepared by Potier's and Greene's group are important precursors to taxol synthesis. After a decade, Holton's group (Tetrahedron Lett., 39, 2883, 1998) provided new methods for the selective acylation and silylation of C(10)-OH of 10-DAB and for the selective silylation of C(7)-OH of 10-DAB. U.S. Pat. No. 5,962,705 (Didier et al) discloses that C(7)-OH and C(10)-OH could be methylated simultaneously to obtained 7,10-dimethoxy-10-DAB. U.S. Pat. No. 5,874,595 discloses a method for preparing baccatin III directed from 10-deacetylbaccatin III comprising: acetylating 10-deacetylbaccatin III with acetic anhydride, a mixed anhydride of acetic acid and any other carboxylic acid or an acetyl halide, and a Lewis acid catalyst.
There is a need for a regioselective method that is applicable to synthesize various taxoids (e.g. paclitaxel, docetaxel, larotaxel, cabazitaxel, and derivatives thereof).
